Method and apparatus for metal rolling



- Jan; 24, 1933. I P. F. WILSON 1,895,303

I METHOD AND APPARATUS FOR METAL ROLLINGP F i'led Ju e 6. 1929 2Sheets-Sheet 1 Jan. 24, 1933.

P. F. WILSON METHOD AND APPARATUS FOR METAL ROLLING Filed June 6, 1929 2Sheets-Sheet 2 INVENTOR Patented Jan- 24, 1933 PARKER F. WILSON, OFWHEELING, WEST VIRGINIA.

METHOD AND APPARATUS FOR METAL ROLLING Application filed June 8, 1929.Serial No. 368,887.

The present invention relates broadly to the art of metal rolling, andmore particularly to the art of so-called continuous mills or continuousstrip rolling in which a given piece of material at certain times isbeing simultaneously operated upon by two or more mills.

In the art of continuous rolling as commercially practiced at thepresent time, it is which for purposes of convenience will hereinafterbe referred to as a billet, into one or more breakdown or roughing millsfrom which it passes into one or more intermediate mills which furtherreduce the thickness of the metal and effect an elongation thereof.After leaving the intermediate mill or mills, the material reduced inthickness and increased in length, is passed into one or more finishingmills which are so set as to reduce the thickness of the metal to therequired point, and effect further elongation thereof.

Depending upon the characteristics of the material which it is desiredto produce, there may be utilized mills either of the two-high,

four-high, or cluster type, the present invention not being limited withrespect to the characteristics or construction of the mills beingutilized. For purposes of illustration,

however, I have diagrammatically shown the invention as practiced withtwo-high mills, it being understood that the utility of the invention isnot limited in this respect.

In accordance with present day operation, it is customary to provideseparate driving motors for each of the various mills, these motors inturn being energized by a motor generator set; Each motor is'in turn soregulated by a suitable field control that the mills will cooperate todeliver material. at a speed at which it can be efiectively handled. Itis apparent, therefore, that the delivery speed of the finishing millsdetermines the speed of operation of the roughing'or breakdown mill ormills. Inasmuch as there is amaximum delivery speed above which materialcannot be satisfactorily or eflic iently handled, there is necessarily amaximum customary to feed an ingot, slab or billet,

entry speed for the material, which speedfrom a practical standpointmust not be exceeded..

It may be assumed for purposes of example that a given continuous millinstallation is effective for producing a reduction of from 10 inches to10/100ths of an inch, with a corres onding elongation of from 10 feet to1000 eet. In the average installation itis not possible to handlematerial delivered at speeds much above 2500 feet a minute.

This being true, it is obviously necessary to so adjust the speed of thevarious mills that there will be an entering speed of'but 25 feet aminute under the above conditions. This being true, it will be apparentto those as skilled in the art that the speed at the entering end of themill represents but a small fraction, namely approximately 1%, of thespeed at the delivery end of the mill. This necessarily means thatconsiderable time is lost in passing the material through the roughingor breakdown mill or mills. This time interval, however, is required inorder to insure a speed of operation of the intermediate and finishingmills such that when the material leaves these mills they will betraveling at the proper relative speed to efficiently act upon andfurther reducev and elongate the material.

The present invention contemplates an improved mill installation andsystem of operation whereby the time ordinarily lost in passing materialthrough the roughing and/or intermediate mills is conserved withouteffecting any increase in the delivery speed.

In the accompanying drawings, I have shown more or lessdiagrammatically, for purposes of illustration only, a preferredembodiment of the present invention.

In the drawings Figure 1 is a diagrammatic side elevational view of atypical installation embodying roughing mills, intermediate mills, andfinishing mills, together with an improved system of control for suchmills; and

Figure 2 is a diagrammatic top plan view of the installation illustratedin Figure 1.

While the present invention contemplates not only the use of anypreferred type of 100 mill, as hereinbefore referred to, but alsocontemplates the use of any desired number of mills in sequence, I haveherein illustrated the invention ascomprising a pair of roughing orbreakdown mills 2; three intermediate mills 3; and four finishing mills4.

The roughing mills are driven by individwhereby they are operated at asubstantially constant speed.

The generator 14 of the motor generator set 8 is connected to thedriving motors 5, for the roughing mills 2. The generator 15 of themotor generator set 9 is similarly connected to the driving motors 6 forthe intermediate mills 3; while the generator 16 is' connected to thedriving motors 7 for the finishing mills 4. v

The generator 14 is provided with a separately excited field 17, oneterminal of which has a connection 18 to a direct current bus line 1.The opposite terminal has a connection 19'to one terminal 20 of arheostat 21.

. Cooperating with the rheostat 21 is a contact arm 22, having aconnection 23 to one terminal 24 of a second rheostat 25. Cooperatingwith the rheostat 25 is a contact arm 26, having a connection 27 to a D.0. bus line 1'.

For actuating the contact arm 22, there is provided a flag 28,operatively connected to one end of a link 29, the opposite end of whichis in turn connected to the contact arm.

' The flag 28 is so located as to be in the path of the material M beingoperated upon,

whereby when the material engages the-flag it will be depressedin suchmanner as to rotate the contact arm 22 against the action of itsreturning spring 30, in a counterclockwise direction, as indicated inFigure 1. This movement of the' flag will be effective (for moving thecontact arm from its full line position of Figure 1, to its dotted lineposition in contact with the terminal 31,

whereby the resistance of the rheostat 21' will be thrown into serieswith the exciting field 17 of the generator 14, thereby correspondinglyreducing the voltage generated by the motor-generator set 8 .andproportionately decreasing the speed of the driving motors 5. I

Assuming the parts to be in full line position illustrated in Figure1,'th e generator 14 will have impressed thereon the maximum voltageofthe exciting coil- 17, whereby the motors 5 will be operated at theirmaximum speed. This speed will be initiall predetermined so that underconditions of? operation as previously referred to by way of exampleonly, the mills 2 will be operated at a speed, for example, ten timesreater than the permissible speed in or assuming the permissiblespeed tobe that determined by the delivery speed of the exciting coil 17 andcorrespondingly reducing the exciting effect of this coil. This in turnwill decrease the voltage output of the generator and thereby reduce thespeed of operation of the motors 5. The resistance of lnaryinstallations,

the rheostat 21 will initially be so selected that the speed reductionof the motors 5 will be such as to properly correlate the speed ofoperation of the roughing mills 2 to the speed of operation of theintermediate mills 3. In other words, the operation-of the flag 28 willeflfect a slowing down of the speed of operation of the roughing millsto a point where the material may be effectively operated upon by theintermediate mills.

This reduced speed condition will continue until such time as thematerial reaches a point where it will be effective for engaging asecond flag 32, similar to the flag 28. The flag 32 has a pivotalconnection ,to one end of a link' 33,-the opposite end of which ispivotally connected to contact arm 26. De- I pression of the flag 32will be effective in the manner described for rotating the contact arm26 in a counter-clockwise direction against action of its returningspring 34 to move the contact arm from engagement with the terminal 24into engagement with theterminal 35. This operation will place theresistance of the rheostat 25 in series with the resistance of therheostat 21, both of these resistances being in series with the excitingcoil 17. This will further reduce the voltage output of the generator 14and effect a furcoil 40 for the generator 15 of the motor generator set9, the opposite terminal of the exciting coil having a connection 41 toing ' mill or mills, automatic speed the bus line 1. The contact arm 36in turn has a connection 42 to the bus line 1.

By reason of the construction just described, movement of the flag 32eflfective for throwing the resistance of the rheostat 25 into serieswith the exciting coil 17, will also be efi'ective for moving thecontact arm 36 from engagement with the terminal 38 into engagement withthe terminal 43 of the rheostat 37, and thus throw its resistance intoseries with the exciting coil 40 for the generator 15.

This, in turn, will be effective for decreasing the generating voltageof the motor generator set 9, and thereby reducing the speed ofoperation of the motors 6. The resistance of the rheostat 37 will beinitially so selected that the speed reduction effected in the motors 6will be such as to properly correlate the speed of operation of theintermediate mills at this time to the reduced speed of operation of theroughing mills, the speed of operation of both of these sets of millsbeing also correlated to the speed of operation of the finishing mills.

It will now be apparent to those skilled in the art that the presentinvention provides a rolling mill installation which may embody one ormore mills in advance of a finishing mill or mills. Where more than .twomills are provided in advance of the finishing mill, the speed of suchmills may be progressively and selectively decreased. This constructionmakes it possible to initially operate one of the mills, for example,the roughing mill, at aspeed materially higher than present dayconditions of operation and without regard to the delivery speed desiredfrom the finishmills. This enables the material being rolled to passthrough the roughing mill or mills in a much smaller time interval thanthat heretofore required. Similarly, when the material has advanced to apoint where it is ready to be engaged by the intermediate controleffects a reduction in the speed of operation of the roughing mill suchthat the roughing mill and intermediate mill have a properly relatedspeed.

This speed is, however, above the normal operating speed of presentinstallations, thereby effecting a reduction in the time required forthe material to travel through the intermediate mill.

The material after passage through the. intermediate mill, is effectivefor producing a further speed reduction in both the roughing mill andintermediate mill, such that their speed of operation will be properlyrelated to the speed of operation of the finishing mill.

This successive reduction in speed of operation of two or moresuccessive mills or groups of mills provides a continuous millinstallation in which the elapsed time from surate with present daydelivery speeds, and

such that the material as delivered may be efliciently handled.

On the other hand, this involves the possibility of a greater totalreduction with one heating than that heretofore permitted, by a prop-erincrease in-the number and arrangement of the mills. In any case, theinvention makes it possible to operate a continuous mill either withoutany reheating between an of the successive rolls or with a considera lereduction in the amount of such reheating.

Such decrease in the elapsed time further results in a considerableincrease in the length of life of the roughing and intermediate rolls.It is a well-known fact that these rolls are subject to very appreciablefire-cracking due to the length of time durin which the hot metal is incontact therewit By reducing this time of contact, the amount offire-cracking is correspondingly reduced, and hence the length of lifeof the rolls correspondingly increased.

In addition to the various advantages referred to, the present inventionhas the further advantage inherent therein of enabling the operator by aproper choice ofspeeds and consequently by a proper selection of elapsedtime intervals, to control and widely vary the metallurgicalcharacteristics of the material being rolled, regardless of whether thatmaterial be a shape or a strip, it being apparent that certa n featuresof the present invention are adaptableto either.

The present invention, of course, contemplates the use of driving motorsof usual characteristics with their individual speed control inaccordance with present day practice, whereby the initial speed isdefinitely controlled bythe operator. In addition to this, the variousrheostats 21, 25 and 37 instead of being of the fixed resistance ty e,may be of the variable resistance type 'undhr the control of theoperator, whereby if the operator Wishes to finish a given piece ofmaterial at a higher temperature, he will throw in relatively lessresistance and thereby increase the speed of rolling throughout. On theother hand, if he wishes tofinish at a lower temperature, the reverseoperation will be resorted to.

It will also be apparentto those skilled in the art that while I haveherein illustrated the flags as being so arranged that they efiect aspeed variation before the material has passed from one roll stand intothe su'cceeeding roll stand, the arrangement may be such that theeffective reduction in speed does not occur until the material. hasactually entered or approximately entered a succeeding roll stand. Inother words, the exact time at which the speed control is effected isnot essential, and the type of control utilized, and its position, maybe such that this variation in speed will occur either before or after asucceeding roll stand comes into operation.

It is also understood that the present invention is not limited withrespect to the speed of a succeeding mill, and thereafter reducingthespeed of operation of said firstmentioned mill, the reduction inspeed being effected while the material being rolled is out of contactwith said succeeding mill.

2. In the method of continuous rolling, the steps comprising operating aplurality of mills at a speed higher than that determined by thedelivery speed of a succeeding mill, and thereafter reducing the speedof operation of said first-mentioned mills, the reduction in speed beingefi'ec-ted while the material being rolled is out of contact with saidsucceeding mill.

3. In the method of continuous rolling, the steps comprising operating aplurality of mills at a speed higher than that determined by thedelivery speed of a succeeding mill, and subsequently sequentiallyreducing the speed of operation of said mills to correspond to the speedof said succeeding mill, the first of said sequential speed reductionsbeing effected while the material being rolled is out of contact withthe second of said plurality of mills, the second of said sequentialspeed reductions being effected while the material being rolled is outof contact with said succeeding mill. I

4. In the continuous rolling of sheets and the like, the stepscomprising changing the speed of at least one of the mills during therolling process. the change in speed bein effected while the materialbeing rolled is in contact with'the mill the speed of which is changed,but before contact of the material with the succeeding mill.

5. In.the continuous rolling of sheets and the like, the stepscomprising passing the material to be rolled through at least one mill,and thereafter reducinggthe speed of said mill to correlate its speedwith the speed of the next succeeding mill, the change in speed beingeflected' While the material is in contact and thereafter decreasing thespeed of said mill to correlate its speed with the speed ofsucceedingmills, the change in speed being effected while the materialis still in contact with said first mentioned mill but before contact ofthe material with said succeeding mills.

7 In the continuous rolling of sheets and the like, the steps comprisingpassingthe material to be rolled through a mill at a speed higher thanthat corresponding to the speed of a, succeeding mill, and thereafterdecreasing the speed of said first-mentioned mill to correspond to thespeed of said succeeding mill, the reduction in speed being effectedwhile the material being rolled is out of contact with said succeedingmill.

8. In the continuous rolling of sheets and the like, the stepscomprising passing the material to be rolled through at least one millat a speed higher than that corresponding to the speed of succeedingmills, and thereafter decreasing the speed of said first mentioned millto correspond to the speed of said sucneeding mills, the change of speedbeing effected While the material is in contact with said firstmentioned mill but before contact with said succeeding mills.

9. In the continuous rolling of sheets and the like, the stepscomprising passing the material'to be rolled through a roughing mill ata speed higher than that corresponding to the speed of a finishing'mill, and thereafter decreasing the speed of the roughing mill tocorrespond to the speed of the finishing mill, the reduction in speedbeing efi'ected while the material being rolled is out of contact withsaid finishing mill.

- 10. In the continuous rolling of sheets and the like wherein aroughing mill, an intermediate mill and a finishing mill are employed,the steps comprising passing the material to be rolled through at leastone roughing mill at a speed higher than that corresponding to the speedof the intermediate mill to correspond to the speed of the intermediatemill while the material is in contact with the roughing mill but beforecontact with the intermediate mill, and thereafter decreasing the speedof ,the, intermediate mill to correspond to the speed of the finishingmill while the material is in contact'with the intermediate mill butbefore contact with the finishing mill.

11. In a continuous rolling mill, a roughing mill, a finishing mill,means for rotating the roughing mill at a speed higher than that mill,decreasing the speed of the roughing to correspond to the speed of thecorresponding to the speed of the finishin mill, and means controlled bythe passage 0 the material throughthe mills for reducing the speed ofthe roughing mill during the rolling operation to correspond to thespeed of the finishing mill before the material bethe finishing mill.

13. In a continuous rolling mill, a roughing mill, a finishin mill,separate motors for the mills, means or rotating the roughing mill at aspeed higher than that corresponding to the speed of the finishing mill,a flag arranged between the roughing and finishing mills in the path ofthe material being rolled, and connections between the flag and themotor of the roughing mill for reducing the 'my hand.-

finishing mill before the sheet enters the finishing mill. Y

16. In the continuous rolling of sheets and the like, the stepscomprising passing the material to be rolled throu h at least one mill,and thereafter reducing t e speed of said mill to correlate its speedwith the speed of the next succeedin mill, the change in speed beingeffected w ile the material is in contact with said first mentioned millbut before ithas been acted upon to a substantial extent by saidsucceeding mill. 7

17. In a continuous rolling mill, a roughing mill, a finishing mill,means for rotating the roughing at a speed higher than thatcorresponding to the speed of the finishing mill, and means forreducingthe speed of the roughing mill during the rollin o eration to correspondto the speed of -t e nishing mill before the material being rolled hasbeen acted upon to a substantial extent by the finishing mill.

In testimony whereof I have hereunto set PARKER F. WILSON.

speed of the roufgmhing mill to correspond to the speed of the shingmill before the 'material enters the finishing mill.

14. In a continuous rolling mill, a rough- .ing m'ill', a finishingmill, separate motors for the mills each connected to separate motorenerator sets, means for rotating the roug ing mill at a speed higherthan that corresponding to the speed of the finishing mill, a flagbetween the roughing and finishinfi mills in the path of the materialbeing r0 ed, and connections between the flag an the motor of the motorgenerator set for the roughing mill for reducing the speed of the.roughing mill to correspond with the speed of the finishing mill beforethe material enters the finishing mill.

15. In a continuous rolling mill, a roughing mill, an intermediate mill,a finishing mill, separate motors for the mills, means for rotating theintermediate mill at a higher speed than that corresponding to the speedof the finishing mill, means for rotating the roughing mill at a speedhigher than that corresponding to the speed of the intermedii ate mill aflag between the roughing and intermediate mills in the path of thematerial being rolled, a second flag between the intermediate mill andthe finishing mill, connections between the first mentioned flag and theroughing mill to reduce the speed of the roughing mill to correspond tothe speed of the intermediate mill before the material venters theintermediate mill, and connections between the second mentioned flag andboth the roughing and intermediate mills to reduce their speeds tocorrespond to the speed of the

